Muscle hypertrophy following 5‐week resistance training using a non‐gravity‐dependent exercise system

Aim: The efficacy of a mechanical, gravity‐independent resistance exercise (RE) system to induce strength gains and muscle hypertrophy was validated. Designed for space crew in orbit, this technique offers resistance during coupled concentric and eccentric actions by utilizing the inertia of a rotating flywheel(s), set in motion by the trainee. Methods: Ten middle‐aged (30–53 years) men and women performed four sets of seven maximal, unilateral (left limb) knee extensions two or three times weekly for 5 weeks. Knee extensor force and electromyographic (EMG) activity of the three superficial quadriceps muscles were measured before and after this intervention. In addition, with the use of magnetic resonance imaging (MRI), volume of individual knee extensor and ankle plantar flexor muscles was assessed. Results: Over the 12 training sessions, the average concentric (CON) and eccentric (ECC) force generated during exercise increased by 11% (P < 0.05). Likewise, maximal isometric strength (maximal voluntary contraction, MVC) at 90 and 120° knee angle increased by (P < 0.05) 11 and 12% respectively, after training. Neither individual quadriceps muscle showed a change (P > 0.05) in maximal integrated EMG (iEMG) activity. Quadriceps muscle volume increased by 6.1% (P < 0.05). Although the magnitude of response varied, all individual quadriceps muscles showed increased (P < 0.05) volume after training. As expected, ankle plantar flexor volume of the trained limb was unchanged (P > 0.05). Likewise, MVC, CON and ECC force, iEMG and knee extensor and plantar flexor muscle volume were unaltered (P > 0.05) in the right, non‐trained limb. Conclusion: The results of this study show that the present RE regimen produces marked muscle hypertrophy and important increases in maximal voluntary strength and appears equally effective as RE paradigms using gravity‐dependent weights, in this regard.     

论空间技术在药用植物研究上的应用

中药现代化的发展需要空间技术的应用。国外空间植物学的研究已经由传统的利用空间条件进行育种、观察染色体变化实验阶段发展到植物生长与人类空间生存一体化研究阶段。我国空间植物学的研究还处于起始阶段 ,实验多在空间育种方面 ,对返回地面的材料进行了较为深入的生长发育、生理生化、遗传变异等基础研究。关于植物搭载设备的研究还比较薄弱 ,植物在太空生长方面的研究还处于空白状态。我国空间技术在药用植物上的应用研究有一定的特色和优势。小型生物舱可以用来搭载药用植物的种子 ,种子太空飞行后可通过仪器检测将种子区分成微重力组和太空射线击中组 ,但遗传育种以及有效成分变化方面的研究明显不足。未来的空间药用植物学研究一方面要探讨药用植物在空间生命支持系统中的作用 ,另一方面还应探讨中药在宇航员飞行过程中的保健作用。     

Safe human exposure limits for airborne linear siloxanes during spaceflight

Abstract

Background: Low molecular weight siloxanes are used in industrial processes and consumer products, and their vapors have been detected in the atmospheres of the Space Shuttle and International Space Station. Therefore, the National Aeronautics and Space Administration (NASA) developed spacecraft maximum allowable concentrations (SMACs) for siloxane vapors to protect astronaut health. Since publication of these original SMACs, new studies and new risk assessment approaches have been published that warrant re-examination of the SMACs.

Objective: To reevaluate SMACs published for octamethyltrisiloxane (L3) for exposures ranging from 1 hour to 180 days, to develop a 1000-day SMAC, and to expand the applicability of those values to the family of linear siloxanes.

Methods: A literature review was conducted to identify studies conducted since the SMACs for L3 were set in 1994. The updated data were reviewed to determine the sensitive toxicity endpoints, and current risk assessment approaches and methods for dosimetric adjustments were evaluated.

Results: Recent data were used to update the original 1-hour, 24-hour, 30-day, and 180-day SMACs for L3, and a 1000-day SMAC was developed to protect crewmembers during future exploration beyond Earth orbit. Group SMACs for the linear siloxane family, including hexamethyldisiloxane (L2), L3, decamethyltetrasiloxane (L4), and dodecamethylpentasiloxane (L5), were set for exposures of 1-hour to 1000 days.

Conclusion: New SMACs, based on acute pulmonary and neurotoxicity at high doses only achievable with L2 and potential liver effects following longer-term exposures to L2 and L3, were established to protect crewmembers from the adverse effects of exposure to linear siloxanes.     

军事孤立封闭环境作业人员标准化神经认知测试的探索

研究军事孤立封闭环境对作业人员认知功能的影响,首先需要一套合格的神经认知测量工具。目前使用的认知测试存在以下问题：不同研究间使用的不一致性;测量的心理过程不明确;存在练习效应;没有针对性的常模数据;灵敏度、难度、全面性不够。据此提出适用于军事孤立封闭环境的神经认知测试应满足如下要求：（1）方便携带,容易开展测试;（2）测试耗时应尽量短（≤30 min）;（3）可重复测量,被试能够较快达到稳定水平;（4）最好是成套测试,检测的认知功能应全面,且必须与完成特定任务密切相关;（5）应有针对军事孤立封闭环境工作人员在一般环境下的常模,以及其随时间变化的测试表现曲线作为对照组数据;（6）认知测试的信效度经过检验;（7）灵敏度较高,测试难度适当;（8）认知测试涉及的心理过程明确且单一,便于解释结果;（9）完成认知测试激活的脑区明确,便于进一步神经心理研究。美国国家航空航天局（NASA）太空飞行认知测试系统Cognition几乎完美契合以上9个要求。未来我军编制神经认知测试时,可在参照Cognition的基础上,着重于提高认知测试装置的便携性、开发计算机自适应认知测验、明确认知测试的纳入标准、开发心理测量学特点一致的平行测验。     

Effects of microgravity on the mouse triceps brachii muscle

Introduction: In this study we investigated the effects of microgravity on the fiber properties of the mouse triceps brachii, a forelimb muscle that has no antigravity function. Methods: Mice (n = 7) were exposed to microgravity for 13 days on the space shuttle Atlantis (Space Transportation System‐135). The fiber cross‐sectional area (CSA) and succinate dehydrogenase (SDH) staining intensity of the triceps brachii muscle were compared with those of controls (n = 7). SDH activity in this muscle was also estimated. Results: Microgravity did not affect the body weight, muscle weight, or fiber CSA, but there was reduced SDH staining intensity of all types of fibers, irrespective of the muscle region (P < 0.05). Microgravity also reduced muscle SDH activity (P < 0.05). Conclusions: Short‐term exposure to microgravity induced a decrease in oxidative capacity, but not atrophy, in the triceps brachii muscle of mice. Muscle Nerve 52 : 63–68, 2015     

医学超声在空间站的应用及展望

超声仪器作为常规的医学影像设备,在临床上已经广泛应用多年,深受广大医务工作者的推崇。自人类载人航天活动以来,超声仪器因具有体积小、质量轻、功耗低、无辐射等优点,成为空间站唯一的医学影像设备,在保障航天员健康和人体生物医学研究方面发挥了不可或缺的作用,并体现了重要的应用价值。本文首先回顾了在空间站上应用超声所取得的研究成果,然后介绍了目前国际空间站超声应用状况,并根据航天飞行中人体常见的变化,结合当今肌肉骨骼超声新技术发展趋势,展望未来超声在航天飞行中的应用前景。     

Molecular biomarkers monitoring human skeletal muscle fibres and microvasculature following long-term bed rest with and without countermeasures

The cellular mechanisms of human skeletal muscle adaptation to disuse are largely unknown. The aim of this study was to determine the morphological and biochemical changes of the lower limb soleus and vastus lateralis muscles following 60 days of head-down tilt bed rest in women with and without exercise countermeasure using molecular biomarkers monitoring functional cell compartments. Muscle biopsies were taken before (pre) and after bed rest (post) from a bed rest-only and a bed rest exercise group (n = 8, each). NOS1 and NOS3/PECAM, markers of myofibre 'activity' and capillary density, and MuRF1 (E3 ubiquitin-ligase), a marker of proteolysis, were documented by confocal immunofluorescence and immunoblot analyses. Morphometrical parameters (myofibre cross-sectional area, type I/II distribution) were largely preserved in muscles from the exercise group with a robust trend for type II hypertrophy in vastus lateralis. In the bed rest-only group, the relative NOS1 immunostaining intensity was decreased at type I and II myofibre membranes, while the bed rest plus exercise group compensated for this loss particularly in soleus. In the microvascular network, NOS3 expression and the capillary-to-fibre ratio were both increased in the exercise group. Elevated MuRF1 immunosignals found in subgroups of atrophic myofibres probably reflected accelerated proteolysis. Immunoblots revealed overexpression of the MuRF1 protein in the soleus of the bed rest-only group (> 35% vs. pre). We conclude that exercise countermeasure during bed rest affected both NOS/NO signalling and proteolysis in female skeletal muscle. Maintenance of NO signalling mechanisms and normal protein turnover by exercise countermeasure may be crucial steps to attenuate human skeletal muscle atrophy and to maintain cell function following chronic disuse.     

Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters

Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes. Twenty-four physically and mentally healthy male volunteers (20–45 years) performed resistive vibration exercise (n=7), resistance exercise without vibration (n=8) or no exercise (n=9) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma. General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD⁺ subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S. We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters. In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise.     

航天食品包装发展需求分析

航天食品包装作为一种特殊的包装形式,对航天食品起最基本的保护作用,同时面对太空飞行和各种复杂严酷太空环境,航天食品包装还要满足重量体积等其他特殊需求。通过初步分析地外驻留、星际飞行等航天任务的过程可以看出,航天食品包装的阻隔性、防护性和再利用率等指标越高越好,而重量越少越好。本文介绍了目前航天食品包装的应用现状和存在的问题,针对后续载人登月及深空探测等任务特点,提出了航天食品包装的使用需求,结合食品包装的发展趋势,探讨了后续任务航天食品包装的研究方向,为载人航天食品包装发展提供参考和借鉴。